System and method for ranging-assisted vehicle positioning

ABSTRACT

Aspects of the present disclosure are directed to device-to-device (D2D) and, more particularly, vehicle-to-vehicle (V2V) communication in which an efficient ranging protocol allows efficient ranging-assisted vehicle positioning. A vehicle transmits a first slot ID in a first control period, to indicate a first time slot for transmitting a first ranging signal in a ranging cycle including a plurality of time slots. The vehicle transmits the first ranging signal in the first time slot in the ranging cycle. From a second vehicle, the first vehicle receives a second ranging signal in a second time slot that is different from the first time slot in the ranging cycle. The first vehicle determines a first time-of-arrival (ToA) of the second ranging signal when received by the first vehicle, and transmits the first ToA in a second control period.

PRIORITY CLAIM

This application claims priority to and the benefit of provisionalpatent application No. 62/611,182 filed in the United States PatentOffice on Dec. 28, 2017, the entire content of which is incorporatedherein by reference as if fully set forth below in its entirety and forall applicable purposes.

TECHNICAL FIELD

The technology discussed below relates generally to wirelesscommunication systems, and more particularly, to ranging-assistedpositioning of vehicles in vehicle-to-vehicle communications.

BACKGROUND

Wireless communication devices, sometimes referred to as user equipment(UE), may communicate with a base station or may communicate directlywith another UE. When a UE communicates directly with another UE, thecommunication is referred to as device-to-device (D2D) communication. Inparticular use cases, a UE may be a wireless communication device, suchas a portable cellular device, or may be a vehicle, such as anautomobile, a drone, or may be any other connected devices. When the UEis a vehicle, such as an automobile, the D2D communication may bereferred to as vehicle-to-vehicle (V2V) communication. Othervehicle-based communications may include vehicle-to-everything (V2X),which may include V2V, vehicle-to-infrastructure (V2I),vehicle-to-network (V2N), and vehicle-to-pedestrian (V2P).Vehicle-to-everything communication and particularly, V2V communicationmay be used in various applications, for example, collision avoidanceand autonomous driving.

BRIEF SUMMARY

The following presents a simplified summary of one or more aspects ofthe present disclosure, in order to provide a basic understanding ofsuch aspects. This summary is not an extensive overview of allcontemplated features of the disclosure, and is intended neither toidentify key or critical elements of all aspects of the disclosure norto delineate the scope of any or all aspects of the disclosure. Its solepurpose is to present some concepts of one or more aspects of thedisclosure in a simplified form as a prelude to the more detaileddescription that is presented later.

One aspect of the disclosure provides a first user equipment (UE) forwireless communication. The first UE includes a transceiver configuredfor performing ranging using a ranging period including a first controlperiod, a ranging cycle, and a second control period. The first UEfurther includes a memory and a processor operatively coupled with thetransceiver and the memory. The processor and the memory are configuredto transmit, via the transceiver, a first slot ID in the first controlperiod, to indicate a first time slot for transmitting a first rangingsignal in the ranging cycle after the first control period. The rangingcycle includes a plurality of time slots including the first time slotand a second time slot. The processor and the memory are furtherconfigured to transmit, via the transceiver, the first ranging signal inthe first time slot in the ranging cycle. The processor and the memoryare further configured to receive, from a second UE via the transceiver,a second ranging signal in a second time slot that is different from thefirst time slot. The processor and the memory are further configured todetermine a first time-of-arrival (ToA) of the second ranging signalwhen received by the first UE and transmit, via the transceiver, thefirst ToA in the second control period after the ranging cycle.

Another aspect of the disclosure provides a first user equipment (UE)for wireless communication. The UE includes a transceiver configured forperforming ranging among a plurality of UEs, a memory, and a processoroperatively coupled with the transceiver and the memory. The processorand the memory are configured to determine an allocation of a pluralityof time slots of a ranging cycle. Each of the UEs is allocated to one ormore of the plurality of time slots for transmitting a ranging signal.The processor and the memory are further configured to transmit, via thetransceiver, a first ranging signal in a time slot allocated to thefirst UE. The processor and the memory are further configured toreceive, from a second UE via the transceiver, a second ranging signalin a time slot allocated to the second UE. The processor and the memoryare further configured to receive, from the second UE via thetransceiver, a first time-of-arrival (ToA) of the first ranging signalwhen received by the second UE. The processor and the memory are furtherconfigured to determine a second ToA of the second ranging signal whenreceived from the first UE. The processor and the memory are furtherconfigured to determine a distance between the first UE and second UEbased on the first ToA and the second ToA.

Another aspect of the disclosure provides a method of performing rangingat a first user equipment (UE) during a ranging period that includes afirst control period, a ranging cycle, and a second control period. Thefirst UE transmits a first slot ID in the first control period, toindicate a first time slot for transmitting a first ranging signal inthe ranging cycle after the first control period. The ranging cycleincludes a plurality of time slots including the first time slot and asecond time slot. The first UE transmits the first ranging signal in thefirst time slot in the ranging cycle. The first UE receives, from asecond UE, a second ranging signal in the second time slot that isdifferent from the first time slot. The first UE determines a firsttime-of-arrival (ToA) of the second ranging signal when received by thefirst UE. Then the first UE transmits the first ToA in the secondcontrol period after the ranging cycle.

Another aspect of the disclosure provides a method of performing rangingamong a plurality of UEs including a first UE and a second UE. The firstUE determines an allocation of a plurality of time slots of a rangingcycle. Each of the UEs is allocated to one or more of the plurality oftime slots for transmitting a ranging signal. The first UE transmits afirst ranging signal in a time slot allocated to the first UE. The firstUE receives, from the second UE, a second ranging signal in a time slotallocated to the second UE. The first UE receives, from the second UE, afirst time-of-arrival (ToA) of the first ranging signal when received bythe second UE. The first UE determines a second ToA of the secondranging signal when received by the first UE. Then, the UE determines adistance between the first UE and second UE based on the first ToA andthe second ToA.

These and other aspects of the invention will become more fullyunderstood upon a review of the detailed description, which follows.Other aspects, features, and embodiments of the present invention willbecome apparent to those of ordinary skill in the art, upon reviewingthe following description of specific, exemplary embodiments of thepresent invention in conjunction with the accompanying figures. Whilefeatures of the present invention may be discussed relative to certainembodiments and figures below, all embodiments of the present inventioncan include one or more of the advantageous features discussed herein.In other words, while one or more embodiments may be discussed as havingcertain advantageous features, one or more of such features may also beused in accordance with the various embodiments of the inventiondiscussed herein. In similar fashion, while exemplary embodiments may bediscussed below as device, system, or method embodiments, it should beunderstood that such exemplary embodiments can be implemented in variousdevices, systems, and methods.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a wireless communication system.

FIG. 2 is a conceptual illustration of an example of a radio accessnetwork.

FIG. 3 is a schematic illustration of an exemplary vehicle-to-everything(V2X) wireless communication network.

FIG. 4 is a schematic illustration of an organization of wirelessresources in an air interface utilizing orthogonal frequency divisionalmultiplexing (OFDM).

FIG. 5 is a block diagram conceptually illustrating an example of ahardware implementation for a scheduling entity according to someaspects of the disclosure.

FIG. 6 is a block diagram conceptually illustrating an example of ahardware implementation for a scheduled entity according to some aspectsof the disclosure.

FIG. 7 is a diagram illustrating a vehicle capable of device-to-devicecommunications according to some aspects of the disclosure.

FIG. 8 is a diagram illustrating a positioning and ranging systemaccording to some aspects of the disclosure.

FIG. 9 is a diagram illustrating a communication timeline of a rangingprotocol according to some aspects of the disclosure.

FIG. 10 is a diagram illustrating an exemplary ranging cycle accordingto some aspects of the disclosure.

FIG. 11 is a diagram illustrating exemplary ranging signal transmissionsduring a ranging cycle according to some aspects of the disclosure.

FIG. 12 is a diagram illustrating an exemplary resource allocation for aranging period according to some aspects of the disclosure.

FIG. 13 is a timing diagram illustrating Time-of-Arrival (ToA)determination of ranging signals according to some aspects of thedisclosure.

FIG. 14 is a flow chart illustrating an exemplary process for performinga ranging operation according to some aspects of the disclosure.

FIG. 15 is a flow chart illustrating another exemplary process forperforming a ranging operation according to some aspects of thedisclosure.

FIG. 16 is a diagram illustrating a positioning process based on rangingaccording to some aspects of the disclosure.

FIG. 17 is a flow chart illustrating an exemplary process fordetermining a position of a device using a ranging based methodaccording to some aspects of the disclosure.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various configurations and isnot intended to represent the only configurations in which the conceptsdescribed herein may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof various concepts. However, it will be apparent to those skilled inthe art that these concepts may be practiced without these specificdetails. In some instances, well-known structures and components areshown in block diagram form in order to avoid obscuring such concepts.

Aspects of the present disclosure are directed to device-to-device (D2D)and, more particularly, vehicle-to-vehicle (V2V) communication using aranging protocol that provides efficient ranging-assisted vehiclepositioning. Accurate vehicle location determination and positioning hasmany potential applications, for example, in collision avoidance andautonomous driving. Various satellite-based location determination andpositioning methods may be used to determine a vehicle's location. Someexemplary Global Navigation Satellite Systems (GNSS) are GlobalPositioning System (GPS), Galileo, GLONASS, BeiDou, etc. A GNSS systemthat uses code phase positioning may provide accuracy of about 2 to 3meters. A GNSS system that uses carrier phase positioning may achievesub-meter accuracy. However, carrier phase positioning may need a longtime period to calculate a fix on the position, so it may be difficultto achieve the accuracy needed in a short duration needed in collisionavoidance and autonomous driving applications. Sub-meter accuracy mayalso be achieved with hybrid positioning using a combination of GNSS,wireless wide area network, wireless local area network, andvision-based positioning. However, hybrid positioning may use additionalinfrastructure and/or a planned route with addition information forpositioning (e.g., crowdsourced or war driven data points along theroute, etc.)

To improve the accuracy of vehicle location determination to the orderof centimeters or better, for example, low-centimeter ranges of one orless than one centimeter (cm) to a few centimeters, relative positioningtechniques may be used. Ranging is a relative positioning technique thatcan determine a distance between and among vehicles and RSUs (road-sideunits). Vehicles and RSUs may be referred to as “UEs” in thisdisclosure. In this disclosure, the term “ranging” refers to measuringand/or determining the distances between pairs of UEs or pairs ofantennas on respective UEs. The measured distances can be combined withknown positions of other UEs (e.g., satellite-based positionsbroadcasted by other UEs) to refine UE position/location estimation.

The various concepts presented throughout this disclosure may beimplemented across a broad variety of telecommunication systems, networkarchitectures, and communication standards. Referring now to FIG. 1, asan illustrative example without limitation, various aspects of thepresent disclosure are illustrated with reference to a wirelesscommunication system 100. The wireless communication system 100 includesthree interacting domains: a core network 102, a radio access network(RAN) 104, and a user equipment (UE) 106. By virtue of the wirelesscommunication system 100, the UE 106 may be enabled to carry out datacommunication with an external data network 110, such as (but notlimited to) the Internet.

The RAN 104 may implement any suitable wireless communication technologyor technologies to provide radio access to the UE 106. As one example,the RAN 104 may operate according to 3^(rd) Generation PartnershipProject (3GPP) New Radio (NR) specifications, often referred to as 5G.As another example, the RAN 104 may operate under a hybrid of 5G NR andEvolved Universal Terrestrial Radio Access Network (eUTRAN) standards,often referred to as LTE. The 3GPP refers to this hybrid RAN as anext-generation RAN, or NG-RAN. Of course, many other examples may beutilized within the scope of the present disclosure.

As illustrated, the RAN 104 includes a plurality of base stations 108.Broadly, a base station is a network element in a radio access networkresponsible for radio transmission and reception in one or more cells toor from a UE. In different technologies, standards, or contexts, a basestation may variously be referred to by those skilled in the art as abase transceiver station (BTS), a radio base station, a radiotransceiver, a transceiver function, a basic service set (BSS), anextended service set (ESS), an access point (AP), a Node B (NB), aneNode B (eNB), a gNode B (gNB), or some other suitable terminology.

The radio access network 104 is further illustrated supporting wirelesscommunication for multiple mobile apparatuses. A mobile apparatus may bereferred to as user equipment (UE) in 3GPP standards, but may also bereferred to by those skilled in the art as a mobile station (MS), asubscriber station, a mobile unit, a subscriber unit, a wireless unit, aremote unit, a mobile device, a wireless device, a wirelesscommunications device, a remote device, a mobile subscriber station, anaccess terminal (AT), a mobile terminal, a wireless terminal, a remoteterminal, a handset, a terminal, a user agent, a mobile client, aclient, or some other suitable terminology. A UE may be an apparatusthat provides a user with access to network services.

Within the present document, a “mobile” apparatus need not necessarilyhave a capability to move, and may be stationary. The term mobileapparatus or mobile device broadly refers to a diverse array of devicesand technologies. For example, some non-limiting examples of a mobileapparatus include a mobile, a cellular (cell) phone, a smart phone, asession initiation protocol (SIP) phone, a laptop, a personal computer(PC), a notebook, a netbook, a smartbook, a tablet, a personal digitalassistant (PDA), and a broad array of embedded systems, e.g.,corresponding to an “Internet of things” (IoT). A mobile apparatus mayadditionally be an automotive or other transportation vehicle, a remotesensor or actuator, a robot or robotics device, a satellite radio, aglobal navigation satellite system (GNSS) device, an object trackingdevice, a drone, a multi-copter, a quad-copter, a remote control device,a consumer and/or wearable device, such as eyewear, a wearable camera, avirtual reality device, a smart watch, a health and/or fitness tracker,a digital audio player (e.g., MP3 player), a camera, a game console,smart apparel, etc. A mobile apparatus may additionally be a digitalhome or smart home device such as a home audio, video, and/or multimediadevice, an appliance, a vending machine, intelligent lighting, a homesecurity system, a smart meter, etc. A mobile apparatus may additionallybe a smart energy device, a security device, a solar panel or solararray, a municipal infrastructure device controlling electric power(e.g., a smart grid), lighting, water, etc.; an industrial automationand enterprise device; a logistics controller; agricultural equipment;military defense equipment, vehicles, aircraft, ships, and weaponry,etc. Still further, a mobile apparatus may provide for connectedmedicine or telemedicine support, i.e., health care at a distance.Telehealth devices may include telehealth monitoring devices andtelehealth administration devices, whose communication may be givenpreferential treatment or prioritized access over other types ofinformation, e.g., in terms of prioritized access for transport ofcritical service data, and/or relevant QoS for transport of criticalservice data.

Wireless communication between a RAN 104 and a UE 106 may be describedas utilizing an air interface. Transmissions over the air interface froma base station (e.g., base station 108) to one or more UEs (e.g., UE106) may be referred to as downlink (DL) transmission. In accordancewith certain aspects of the present disclosure, the term downlink mayrefer to a point-to-multipoint transmission originating at a schedulingentity (described further below; e.g., base station 108). Another way todescribe this scheme may be to use the term broadcast channelmultiplexing. Transmissions from a UE (e.g., UE 106) to a base station(e.g., base station 108) may be referred to as uplink (UL)transmissions. In accordance with further aspects of the presentdisclosure, the term uplink may refer to a point-to-point transmissionoriginating at a scheduled entity (described further below; e.g., UE106).

In some examples, access to the air interface may be scheduled, whereina scheduling entity (e.g., a base station 108) allocates resources forcommunication among some or all devices and equipment within its servicearea or cell. Within the present disclosure, as discussed further below,the scheduling entity may be responsible for scheduling, assigning,reconfiguring, and releasing resources for one or more scheduledentities. That is, for scheduled communication, UEs 106, which may bescheduled entities, may utilize resources allocated by the schedulingentity 108.

Base stations 108 are not the only entities that may function asscheduling entities. That is, in some examples, a UE may function as ascheduling entity, scheduling resources for one or more scheduledentities (e.g., one or more other UEs).

As illustrated in FIG. 1, a scheduling entity 108 may broadcast downlinktraffic 112 to one or more scheduled entities 106. Broadly, thescheduling entity 108 is a node or device responsible for schedulingtraffic in a wireless communication network, including the downlinktraffic 112 and, in some examples, uplink traffic 116 from one or morescheduled entities 106 to the scheduling entity 108. On the other hand,the scheduled entity 106 is a node or device that receives downlinkcontrol information 114, including but not limited to schedulinginformation (e.g., a grant), synchronization or timing information, orother control information from another entity in the wirelesscommunication network such as the scheduling entity 108.

In general, base stations 108 may include a backhaul interface forcommunication with a backhaul portion 120 of the wireless communicationsystem. The backhaul 120 may provide a link between a base station 108and the core network 102. Further, in some examples, a backhaul networkmay provide interconnection between the respective base stations 108.Various types of backhaul interfaces may be employed, such as a directphysical connection, a virtual network, or the like using any suitabletransport network.

The core network 102 may be a part of the wireless communication system100, and may be independent of the radio access technology used in theRAN 104. In some examples, the core network 102 may be configuredaccording to 5G standards (e.g., 5GC). In other examples, the corenetwork 102 may be configured according to a 4G evolved packet core(EPC), or any other suitable standard or configuration.

Referring now to FIG. 2, by way of example and without limitation, aschematic illustration of a RAN 200 is provided. In some examples, theRAN 200 may be the same as the RAN 104 described above and illustratedin FIG. 1. The geographic area covered by the RAN 200 may be dividedinto cellular regions (cells) that can be uniquely identified by a userequipment (UE) based on an identification broadcasted from one accesspoint or base station. FIG. 2 illustrates macrocells 202, 204, and 206,and a small cell 208, each of which may include one or more sectors (notshown). A sector is a sub-area of a cell. All sectors within one cellare served by the same base station. A radio link within a sector can beidentified by a single logical identification belonging to that sector.In a cell that is divided into sectors, the multiple sectors within acell can be formed by groups of antennas with each antenna responsiblefor communication with UEs in a portion of the cell.

In FIG. 2, two base stations 210 and 212 are shown in cells 202 and 204;and a third base station 214 is shown controlling a remote radio head(RRH) 216 in cell 206. That is, a base station can have an integratedantenna or can be connected to an antenna or RRH by feeder cables. Inthe illustrated example, the cells 202, 204, and 126 may be referred toas macrocells, as the base stations 210, 212, and 214 support cellshaving a large size. Further, a base station 218 is shown in the smallcell 208 (e.g., a microcell, picocell, femtocell, home base station,home Node B, home eNode B, etc.) which may overlap with one or moremacrocells. In this example, the cell 208 may be referred to as a smallcell, as the base station 218 supports a cell having a relatively smallsize. Cell sizing can be done according to system design as well ascomponent constraints.

It is to be understood that the radio access network 200 may include anynumber of wireless base stations and cells. Further, a relay node may bedeployed to extend the size or coverage area of a given cell. The basestations 210, 212, 214, 218 provide wireless access points to a corenetwork for any number of mobile apparatuses. In some examples, the basestations 210, 212, 214, and/or 218 may be the same as the basestation/scheduling entity 108 described above and illustrated in FIG. 1.

FIG. 2 further includes a quadcopter or drone 220, which may beconfigured to function as a base station. That is, in some examples, acell may not necessarily be stationary, and the geographic area of thecell may move according to the location of a mobile base station such asthe quadcopter 220.

Within the RAN 200, the cells may include UEs that may be incommunication with one or more sectors of each cell. Further, each basestation 210, 212, 214, 218, and 220 may be configured to provide anaccess point to a core network 102 (see FIG. 1) for all the UEs in therespective cells. For example, UEs 222 and 224 may be in communicationwith base station 210; UEs 226 and 228 may be in communication with basestation 212; UEs 230 and 232 may be in communication with base station214 by way of RRH 216; UE 234 may be in communication with base station218; and UE 236 may be in communication with mobile base station 220. Insome examples, the UEs 222, 224, 226, 228, 230, 232, 234, 236, 238, 240,and/or 242 may be the same as the UE/scheduled entity 106 describedabove and illustrated in FIG. 1. In some examples, some of the UEs maybe a vehicle or automobile (e.g., UE 224).

In some examples, a mobile network node (e.g., quadcopter 220 or vehicle224) may be configured to function as a UE. For example, the quadcopter220 may operate within cell 202 by communicating with base station 210.

In a further aspect of the RAN 200, sidelink signals may be used betweenUEs without necessarily relying on scheduling or control informationfrom a base station. For example, two or more UEs (e.g., UEs 226 and228) may communicate with each other using peer to peer (P2P) orsidelink signals 227 without relaying that communication through a basestation (e.g., base station 212). In a further example, UE 238 isillustrated communicating with UEs 240 and 242. Here, the UE 238 mayfunction as a scheduling entity or a primary sidelink device, and UEs240 and 242 may function as a scheduled entity or a non-primary (e.g.,secondary) sidelink device. In still another example, a UE may functionas a scheduling entity in a device-to-device (D2D), peer-to-peer (P2P),or vehicle-to-vehicle (V2V) network, and/or in a mesh network. In a meshnetwork example, UEs 240 and 242 may optionally communicate directlywith one another in addition to communicating with the scheduling entity238. Thus, in a wireless communication system with scheduled access totime-frequency resources and having a cellular configuration, a P2Pconfiguration, or a mesh configuration, a scheduling entity and one ormore scheduled entities may communicate utilizing the scheduledresources.

In the radio access network 200, the ability for a UE (e.g., vehicle240) to communicate while moving, independent of its location, isreferred to as mobility. The various physical channels between the UEand the radio access network are generally set up, maintained, andreleased under the control of an access and mobility management function(AMF, not illustrated, part of the core network 102 in FIG. 1), whichmay include a security context management function (SCMF) that managesthe security context for both the control plane and the user planefunctionality, and a security anchor function (SEAF) that performsauthentication.

In various aspects of the disclosure, a radio access network 200 mayutilize DL-based mobility or UL-based mobility to enable mobility andhandovers (i.e., the transfer of a UE's connection from one radiochannel to another). In a network configured for DL-based mobility,during a call with a scheduling entity, or at any other time, a UE maymonitor various parameters of the signal from its serving cell as wellas various parameters of neighboring cells. Depending on the quality ofthese parameters, the UE may maintain communication with one or more ofthe neighboring cells. During this time, if the UE moves from one cellto another, or if signal quality from a neighboring cell exceeds thatfrom the serving cell for a given amount of time, the UE may undertake ahandoff or handover from the serving cell to the neighboring (target)cell. For example, UE 224 (illustrated as a vehicle, although anysuitable form of UE may be used) may move from the geographic areacorresponding to its serving cell 202 to the geographic areacorresponding to a neighbor cell 206. When the signal strength orquality from the neighbor cell 206 exceeds that of its serving cell 202for a given amount of time, the UE 224 may transmit a reporting messageto its serving base station 210 indicating this condition. In response,the UE 224 may receive a handover command, and the UE may undergo ahandover to the cell 206.

In a network configured for UL-based mobility, UL reference signals fromeach UE may be utilized by the network to select a serving cell for eachUE. In some examples, the base stations 210, 212, and 214/216 maybroadcast unified synchronization signals (e.g., unified PrimarySynchronization Signals (PSSs), unified Secondary SynchronizationSignals (SSSs) and unified Physical Broadcast Channels (PBCH)). The UEs222, 224, 226, 228, 230, and 232 may receive the unified synchronizationsignals, derive the carrier frequency and slot timing from thesynchronization signals, and in response to deriving timing, transmit anuplink pilot or reference signal. The uplink pilot signal transmitted bya UE (e.g., UE 224) may be concurrently received by two or more cells(e.g., base stations 210 and 214/216) within the radio access network200. Each of the cells may measure a strength of the pilot signal, andthe radio access network (e.g., one or more of the base stations 210 and214/216 and/or a central node within the core network) may determine aserving cell for the UE 224. As the UE 224 moves through the radioaccess network 200, the network may continue to monitor the uplink pilotsignal transmitted by the UE 224. When the signal strength or quality ofthe pilot signal measured by a neighboring cell exceeds that of thesignal strength or quality measured by the serving cell, the network 200may handover the UE 224 from the serving cell to the neighboring cell,with or without informing the UE 224.

Although the synchronization signal transmitted by the base stations210, 212, and 214/216 may be unified, the synchronization signal may notidentify a particular cell, but rather may identify a zone of multiplecells operating on the same frequency and/or with the same timing. Theuse of zones in 5G networks or other next-generation communicationnetworks enables the uplink-based mobility framework and improves theefficiency of both the UE and the network, since the number of mobilitymessages that need to be exchanged between the UE and the network may bereduced.

In various implementations, the air interface in the radio accessnetwork 200 may utilize licensed spectrum, unlicensed spectrum, orshared spectrum. Licensed spectrum provides for exclusive use of aportion of the spectrum, generally by virtue of a mobile networkoperator purchasing a license from a government regulatory body.Unlicensed spectrum provides for shared use of a portion of the spectrumwithout need for a government-granted license. While compliance withsome technical rules is generally still required to access unlicensedspectrum, generally, any operator or device may gain access. Sharedspectrum may fall between licensed and unlicensed spectrum, whereintechnical rules or limitations may be required to access the spectrum,but the spectrum may still be shared by multiple operators and/ormultiple RATs. For example, the holder of a license for a portion oflicensed spectrum may provide licensed shared access (LSA) to share thatspectrum with other parties, e.g., with suitable licensee-determinedconditions to gain access.

The air interface in the radio access network 200 may utilize one ormore duplexing algorithms. Duplex refers to a point-to-pointcommunication link where both endpoints can communicate with one anotherin both directions. Full duplex means both endpoints can simultaneouslycommunicate with one another. Half duplex means only one endpoint cansend information to the other at a time. In a wireless link, a fullduplex channel generally relies on physical isolation of a transmitterand receiver, and suitable interference cancellation technologies. Fullduplex emulation is frequently implemented for wireless links byutilizing frequency division duplex (FDD) or time division duplex (TDD).In FDD, transmissions in different directions operate at differentcarrier frequencies. In TDD, transmissions in different directions on agiven channel are separated from one another using time divisionmultiplexing. That is, at some times the channel is dedicated fortransmissions in one direction, while at other times the channel isdedicated for transmissions in the other direction, where the directionmay change very rapidly, e.g., several times per slot.

In order for transmissions over the radio access network 200 to obtain alow block error rate (BLER) while still achieving very high data rates,channel coding may be used. That is, wireless communication maygenerally utilize a suitable error correcting block code. In a typicalblock code, an information message or sequence is split up into codeblocks (CBs), and an encoder (e.g., a CODEC) at the transmitting devicethen mathematically adds redundancy to the information message.Exploitation of this redundancy in the encoded information message canimprove the reliability of the message, enabling correction for any biterrors that may occur due to the noise.

In 5G NR specifications, user data may be coded using quasi-cycliclow-density parity check (LDPC) with two different base graphs: one basegraph is used for large code blocks and/or high code rates, while theother base graph is used otherwise. Control information and the physicalbroadcast channel (PBCH) are coded using Polar coding, based on nestedsequences. For these channels, puncturing, shortening, and repetitionare used for rate matching.

However, those of ordinary skill in the art will understand that aspectsof the present disclosure may be implemented utilizing any suitablechannel code. Various implementations of scheduling entities 108 andscheduled entities 106 may include suitable hardware and capabilities(e.g., an encoder, a decoder, and/or a CODEC) to utilize one or more ofthese channel codes for wireless communication.

The air interface in the radio access network 200 may utilize one ormore multiplexing and multiple access algorithms to enable simultaneouscommunication of the various devices. For example, 5G NR specificationsprovide multiple access for UL transmissions from UEs 222 and 224 tobase station 210, and for multiplexing for DL transmissions from basestation 210 to one or more UEs 222 and 224, utilizing orthogonalfrequency division multiplexing (OFDM) with a cyclic prefix (CP). Inaddition, for UL transmissions, 5G NR specifications provide support fordiscrete Fourier transform-spread-OFDM (DFT-s-OFDM) with a CP (alsoreferred to as single-carrier FDMA (SC-FDMA)). However, within the scopeof the present disclosure, multiplexing and multiple access are notlimited to the above schemes, and may be provided utilizing timedivision multiple access (TDMA), code division multiple access (CDMA),frequency division multiple access (FDMA), sparse code multiple access(SCMA), resource spread multiple access (RSMA), or other suitablemultiple access schemes. Further, multiplexing DL transmissions from thebase station 210 to UEs 222 and 224 may be provided utilizing timedivision multiplexing (TDM), code division multiplexing (CDM), frequencydivision multiplexing (FDM), orthogonal frequency division multiplexing(OFDM), sparse code multiplexing (SCM), or other suitable multiplexingschemes.

V2X Communication Network

FIG. 3 illustrates an exemplary vehicle-to-everything (V2X)communication network 300. A V2X network can connect vehicles 302 a and302 b to each other (vehicle-to-vehicle (V2V)), to roadsideinfrastructure 304 (vehicle-to-infrastructure (V2I)), to pedestrians 306(vehicle-to-pedestrian (V2P)), and/or to the network/base station 308(vehicle-to-network (V2N)). The network 300 may be a part of the network200 described in relation to FIG. 2. In some aspects of the disclosure,a vehicle may be a self-powered vehicle (e.g., electric or gas powered).In some aspects of the disclosure, a vehicle may be a manually poweredvehicle (e.g., a bicycle). In some aspects of the disclosure, a vehiclemay be autonomous, semi-autonomous, or manually operated.

A V2I transmission may be between a vehicle (e.g., vehicle 302 a) and aroadside unit (RSU) 304, which may be coupled to variousinfrastructures, such as a traffic light, building, streetlight, trafficcamera, tollbooth, or other stationary object. In some examples, the RSU304 may act as a base station enabling communication between vehicles302 a and 302 b, between vehicles 302 a/302 b and the RSU 304, andbetween vehicles 302 a/302 b and mobile devices 306 of pedestrians. TheRSU 304 may further exchange V2X data gathered from the surroundingenvironment, such as a connected traffic camera or traffic lightcontroller, V2X connected vehicles 302 a/302 b, and mobile devices 306of pedestrians, with other RSUs 304 and distribute that V2X data to V2Xconnected vehicles 302 a/302 b and pedestrians 306. Examples of V2X datamay include status information (e.g., position, speed, acceleration,trajectory, etc.) or event information (e.g., traffic jam, icy road,fog, pedestrian crossing the road, collision, etc.), and may alsoinclude video data captured by a camera on a vehicle or coupled to anRSU 304.

Such V2X data may enable autonomous driving and improve road safety andtraffic efficiency. For example, the exchanged V2X data or messages maybe utilized by a V2X connected vehicle 302 a/302 b to provide in-vehiclecollision warnings, road hazard warnings, approaching emergency vehiclewarnings, pre-/post-crash warnings and information, emergency brakewarnings, traffic jam ahead warnings, lane change warnings, intelligentnavigation services, and other similar information. V2X (e.g., V2V)communication may be used for ranging operations between UEs todetermine a distance between the UEs. In addition, V2X data received bya V2X connected mobile device 306 of a pedestrian may be utilized totrigger a warning sound, vibration, flashing light, etc., in case ofimminent danger (e.g., approaching vehicle).

V2N communication may utilize traditional cellular links to providecloud services to a V2X device (e.g., a vehicle 302 a/302 b, RSU 304, orpedestrian 306) for latency-tolerant use cases. For example, V2N mayenable a V2X network server to broadcast messages (e.g., weather,traffic, or other information) to V2X devices over a wide area networkand may enable V2X devices to send unicast messages to the V2X networkserver. In addition, V2N communication may provide backhaul services forRSUs 304.

Due to the usual high mobility of vehicles, it is desirable to performranging operations among vehicles (e.g., vehicles 320 a and 302 b) in ashort period of time to provide a snapshot of a vehicle's position. Inone example, when two vehicles travel at 140 km/h on a highway inopposite directions, their absolute positions change by 3.89 meters in100 milliseconds (ms), and the relative positions of the vehiclestraveling in opposite directions changes by 7.78 meters. If the rangingsignals are sent in a span of 100 ms, then during that time thepositions of the vehicles may have changed by a few meters. This leadsto inaccurate or outdated estimation of positions even if the rangingoperation is very accurate. Therefore, it is desirable to concentratethe ranging signals that are transmitted within a short period of time.

In some aspects of the disclosure, the ranging signals sent by differentvehicles occur very close in time to provide a “snapshot” of thevehicles' position. If ranging signals are transmitted between each pairof UEs among N UEs, then O(N²) (i.e., order of the magnitude requiredfor the number of ranging signals to be transmitted) ranging signals areneeded, which is more than what is considered acceptable given thevehicles' anticipated speed and location change per unit of time.Another challenge for accurate ranging includes time offsets (clockoffsets) between the UEs, which needs to be compensated to derive thecorrect distance between UEs.

Aspects of the present disclosure provide a ranging protocol in whichthe ranging signals are concentrated in a very short period of time toachieve highly accurate ranging. Ranging in a small time window ensuresthat any clock drifts of the UEs are small during the window. This canavoid the need for clock drift estimation and simplify the rangingprotocol. Moreover, the disclosed ranging protocol may have a low dutycycle to improve efficiency in energy and resource usage.

Various aspects of the present disclosure will be described withreference to an OFDM waveform, schematically illustrated in FIG. 4. Itshould be understood by those of ordinary skill in the art that thevarious aspects of the present disclosure may be applied to aDFT-s-OFDMA waveform in substantially the same way as described hereinbelow. That is, while some examples of the present disclosure may focuson an OFDM link for clarity, it should be understood that the sameprinciples may be applied as well to DFT-s-OFDMA waveforms and others.

Within the present disclosure, a frame refers to a predeterminedduration (e.g., 10 ms) for wireless transmissions, with each frameconsisting of a predetermined number of subframes (e.g., 10 subframes of1 ms each). On a given carrier, there may be one set of frames in theUL, and another set of frames in the DL. Referring now to FIG. 4, anexpanded view of an exemplary DL subframe 402 is illustrated, showing anOFDM resource grid 404. However, as those skilled in the art willreadily appreciate, the PHY transmission structure for any particularapplication may vary from the example described here, depending on anynumber of factors. Here, time is in the horizontal direction with unitsof OFDM symbols; and frequency is in the vertical direction with unitsof subcarriers or tones.

The resource grid 404 may be used to schematically representtime-frequency resources for a given antenna port. For example, in amultiple-input multiple-output (MIMO) implementation with multipleantenna ports available, a corresponding multiple numbers of resourcegrids 404 may be available for communication. The resource grid 404 isdivided into multiple resource elements (REs) 406. An RE, which is 1subcarrier×1 symbol, is the smallest discrete part of the time-frequencygrid, and contains a single complex value representing data from aphysical channel or signal. Depending on the modulation utilized in aparticular implementation, each RE may represent one or more bits ofinformation. In some examples, a block of REs may be referred to as aphysical resource block (PRB) or more simply a resource block (RB) 408,which contains any suitable number of consecutive subcarriers in thefrequency domain. In one example, an RB may include 12 subcarriers, anumber independent of the numerology used. In some examples, dependingon the numerology, an RB may include any suitable number of consecutiveOFDM symbols in the time domain. Within the present disclosure, it isassumed that a single RB such as the RB 408 entirely corresponds to asingle direction of communication (either transmission or reception fora given device).

A UE generally utilizes only a subset of the resource grid 404. An RBmay be the smallest unit of resources that can be allocated to a UE.Thus, the more RBs scheduled for a UE, and the higher the modulationscheme chosen for the air interface, the higher the data rate for theUE.

In this illustration, the RB 408 is shown as occupying less than theentire bandwidth of the subframe 402, with some subcarriers illustratedabove and below the RB 408. In a given implementation, the subframe 402may have a bandwidth corresponding to any number of one or more RBs 408.Further, in this illustration, the RB 408 is shown as occupying lessthan the entire duration of the subframe 402, although this is merelyone possible example.

Each subframe 402 may consist of one or multiple adjacent slots. In theexample shown in FIG. 4, one subframe 402 includes four slots 410, as anillustrative example. In some examples, a slot may be defined accordingto a specified number of OFDM symbols with a given cyclic prefix (CP)length. For example, a slot may include 7 or 14 OFDM symbols with anominal CP. Additional examples may include mini-slots having a shorterduration (e.g., one or two OFDM symbols). These mini-slots may in somecases be transmitted occupying resources scheduled for ongoing slottransmissions for the same or for different UEs.

An expanded view of one of the slots 410 illustrates the slot 410including a control region 412 and a data region 414. In general, thecontrol region 412 may carry control channels (e.g., PDCCH), and thedata region 414 may carry data channels (e.g., PDSCH or PUSCH). Ofcourse, a slot may contain all DL, all UL, or at least one DL portionand at least one UL portion. The simple structure illustrated in FIG. 4is merely exemplary in nature, and different slot structures may beutilized, and may include one or more of each of the control region(s)and data region(s).

Although not illustrated in FIG. 4, the various REs 406 within a RB 408may be scheduled to carry one or more physical channels, includingcontrol channels, shared channels, data channels, etc. Other REs 406within the RB 408 may also carry pilots or reference signals, includingbut not limited to a demodulation reference signal (DMRS) a controlreference signal (CRS), a sounding reference signal (SRS), or apositioning reference signal (PRS). These pilots or reference signalsmay provide for a receiving device to perform channel estimation of thecorresponding channel, which may enable coherent demodulation/detectionof the control and/or data channels within the RB 408.

In a DL transmission, the transmitting device (e.g., the schedulingentity 108) may allocate one or more REs 406 (e.g., within a controlregion 412) to carry DL control information 114 including one or more DLcontrol channels that generally carry information originating fromhigher layers, such as a physical broadcast channel (PBCH), a physicaldownlink control channel (PDCCH), etc., to one or more scheduledentities 106. In addition, DL REs may be allocated to carry DL physicalsignals that generally do not carry information originating from higherlayers. These DL physical signals may include a primary synchronizationsignal (PSS); a secondary synchronization signal (SSS); demodulationreference signals (DM-RS); phase-tracking reference signals (PT-RS);channel-state information reference signals (CSI-RS); etc.

The synchronization signals PSS and SSS (collectively referred to asSS), and in some examples, the PBCH, may be transmitted in an SS blockthat includes 4 consecutive OFDM symbols, numbered via a time index inincreasing order from 0 to 3. In the frequency domain, the SS block mayextend over 240 contiguous subcarriers, with the subcarriers beingnumbered via a frequency index in increasing order from 0 to 239. Ofcourse, the present disclosure is not limited to this specific SS blockconfiguration. Other nonlimiting examples may utilize greater or fewerthan two synchronization signals; may include one or more supplementalchannels in addition to the PBCH; may omit a PBCH; and/or may utilizenonconsecutive symbols for an SS block, within the scope of the presentdisclosure.

The PDCCH may carry downlink control information (DCI) for one or moreUEs in a cell, including but not limited to power control commands,scheduling information, a grant, and/or an assignment of REs for DL andUL transmissions.

In an UL transmission, the transmitting device (e.g., the scheduledentity 106) may utilize one or more REs 406 to carry UL controlinformation 118 originating from higher layers via one or more ULcontrol channels, such as a physical uplink control channel (PUCCH), aphysical random access channel (PRACH), etc., to the scheduling entity108. Further, UL REs may carry UL physical signals that generally do notcarry information originating from higher layers, such as demodulationreference signals (DM-RS), phase-tracking reference signals (PT-RS),sounding reference signals (SRS), etc. In some examples, the controlinformation 118 may include a scheduling request (SR), i.e., a requestfor the scheduling entity 108 to schedule uplink transmissions. Here, inresponse to the SR transmitted on the control channel 118, thescheduling entity 108 may transmit downlink control information 114 thatmay schedule resources for uplink packet transmissions. UL controlinformation may also include hybrid automatic repeat request (HARQ)feedback such as an acknowledgment (ACK) or negative acknowledgment(NACK), channel state information (CSI), or any other suitable ULcontrol information. HARQ is a technique well-known to those of ordinaryskill in the art, wherein the integrity of packet transmissions may bechecked at the receiving side for accuracy, e.g., utilizing any suitableintegrity checking mechanism, such as a checksum or a cyclic redundancycheck (CRC). If the integrity of the transmission confirmed, an ACK maybe transmitted, whereas if not confirmed, a NACK may be transmitted. Inresponse to a NACK, the transmitting device may send a HARQretransmission, which may implement chase combining, incrementalredundancy, etc.

In addition to control information, one or more REs 406 (e.g., withinthe data region 414) may be allocated for user data or traffic data.Such traffic may be carried on one or more traffic channels, such as,for a DL transmission, a physical downlink shared channel (PDSCH); orfor an UL transmission, a physical uplink shared channel (PUSCH). Insome aspects of the disclosure, some REs 406 may be allocated for V2Xcommunication, for example, ranging operations.

The channels or carriers described above are not necessarily all thechannels or carriers that may be utilized between a scheduling entity108 and scheduled entities 106, and those of ordinary skill in the artwill recognize that other channels or carriers may be utilized inaddition to those illustrated, such as other traffic, control, andfeedback channels.

These physical channels described above are generally multiplexed andmapped to transport channels for handling at the medium access control(MAC) layer. Transport channels carry blocks of information calledtransport blocks (TB). The transport block size (TBS), which maycorrespond to a number of bits of information, may be a controlledparameter, based on the modulation and coding scheme (MCS) and thenumber of RBs in a given transmission.

FIG. 5 is a block diagram illustrating an example of a hardwareimplementation for a scheduling entity 500 employing a processing system514. For example, the scheduling entity 500 may be a user equipment (UE)or vehicle as illustrated in any one or more of FIGS. 1, 2, 3, 7, 8and/or 11. In another example, the scheduling entity 500 may be a basestation as illustrated in any one or more of FIGS. 1, 2, 3, 7, 8, and/or11.

The scheduling entity 500 may be implemented with a processing system514 that includes one or more processors 504. Examples of processors 504include microprocessors, microcontrollers, digital signal processors(DSPs), field programmable gate arrays (FPGAs), programmable logicdevices (PLDs), state machines, gated logic, discrete hardware circuits,and other suitable hardware configured to perform the variousfunctionality described throughout this disclosure. In various examples,the scheduling entity 500 may be configured to perform any one or moreof the functions described herein. That is, the processor 504, asutilized in a scheduling entity 500, may be used to implement any one ormore of the processes and procedures described below and illustrated inFIGS. 7-17.

In this example, the processing system 514 may be implemented with a busarchitecture, represented generally by the bus 502. The bus 502 mayinclude any number of interconnecting buses and bridges depending on thespecific application of the processing system 514 and the overall designconstraints. The bus 502 communicatively couples together variouscircuits including one or more processors (represented generally by theprocessor 504), a memory 505, and computer-readable media (representedgenerally by the computer-readable medium 506). The bus 502 may alsolink various other circuits such as timing sources, peripherals, voltageregulators, and power management circuits, which are well known in theart, and therefore, will not be described any further. A bus interface508 provides an interface between the bus 502 and a transceiver 510. Thetransceiver 510 provides a communication interface or means forcommunicating with various other apparatus over a transmission medium.Depending upon the nature of the apparatus, a user interface 512 (e.g.,keypad, display, speaker, microphone, joystick) may also be provided. Ofcourse, such a user interface 512 is optional, and may be omitted insome examples, such as a base station.

In some aspects of the disclosure, the processor 504 may includecircuitry (e.g., a processing circuit 540, a ranging configurationcircuit 542, and a communication circuit 544) configured to implementone or more of the functions described below in relation to FIGS. 7-17.The processing circuit 540 may be configured to perform various dataprocessing functions used in wireless communication. The rangingconfiguration circuit 542 may be configured to determine, allocate, andschedule radio and network resources for use in ranging operations in aV2X network. In one example, the ranging configuration circuit 542 mayallocate various radio resources to ranging operations in a V2X network300. The communication circuit 544 may be configured to perform variouswireless communication functions using the transceiver 510 and anantenna 516.

The processor 504 is responsible for managing the bus 502 and generalprocessing, including the execution of software stored on thecomputer-readable medium 506. The software, when executed by theprocessor 504, causes the processing system 514 to perform the variousfunctions described below for any particular apparatus. Thecomputer-readable medium 506 and the memory 505 may also be used forstoring data that is manipulated by the processor 504 when executingsoftware.

One or more processors 504 in the processing system may execute softwareor code. Software shall be construed broadly to mean instructions,instruction sets, code, code segments, program code, programs,subprograms, software modules, applications, software applications,software packages, routines, subroutines, objects, executables, threadsof execution, procedures, functions, etc., whether referred to assoftware, firmware, middleware, microcode, hardware descriptionlanguage, or otherwise. The software may reside on a computer-readablemedium 506. The computer-readable medium 506 may be a non-transitorycomputer-readable medium. A non-transitory computer-readable mediumincludes, by way of example, a magnetic storage device (e.g., hard disk,floppy disk, magnetic strip), an optical disk (e.g., a compact disc (CD)or a digital versatile disc (DVD)), a smart card, a flash memory device(e.g., a card, a stick, or a key drive), a random access memory (RAM), aread only memory (ROM), a programmable ROM (PROM), an erasable PROM(EPROM), an electrically erasable PROM (EEPROM), a register, a removabledisk, and any other suitable medium for storing software and/orinstructions that may be accessed, read, and executed by a computer. Thecomputer-readable medium 506 may reside in the processing system 514,external to the processing system 514, or distributed across multipleentities including the processing system 514. The computer-readablemedium 506 may be embodied in a computer program product. By way ofexample, a computer program product may include a computer-readablemedium in packaging materials. Those skilled in the art will recognizehow best to implement the described functionality presented throughoutthis disclosure depending on the particular application and the overalldesign constraints imposed on the overall system.

In one or more examples, the computer-readable storage medium 506 mayinclude software or executable code (e.g., processing instructions 550,ranging configuration instructions 552, and communication instructions554) configured for various functions. For example, the software may beconfigured to implement one or more of the ranging functions describedin relation to FIGS. 7-17. The processing instructions 550 may configurethe processor 504 to perform various data processing functions using inwireless communication. The ranging configuration instructions 552 mayconfigure the processor 504 to determine, allocate, and schedule radioand network resources for use in ranging operations in a V2X network.The communication instructions 554 may configure the processor 504 toperform various wireless communication functions using the transceiver510.

FIG. 6 is a conceptual diagram illustrating an example of a hardwareimplementation for an exemplary scheduled entity 600 employing aprocessing system 614. In accordance with various aspects of thedisclosure, an element, or any portion of an element, or any combinationof elements may be implemented with a processing system 614 thatincludes one or more processors 604. For example, the scheduled entity600 may be a user equipment (UE) or vehicle as illustrated in any one ormore of FIGS. 1, 2, 3, 7, 8, and/or 11.

The processing system 614 may be substantially the same as theprocessing system 514 illustrated in FIG. 5, including a bus interface608, a bus 602, memory 605, a processor 604, and a computer-readablemedium 606. Furthermore, the scheduled entity 600 may include a userinterface 612 and a transceiver 610 substantially similar to thosedescribed above in FIG. 5. That is, the processor 604, as utilized in ascheduled entity 600, may be used to implement any one or more of theprocesses described below and illustrated in FIGS. 7-17.

In some aspects of the disclosure, the processor 604 may includecircuitry (e.g., a processing circuit 640, a ranging circuit 642, and acommunication circuit 644) configured to implement one or more of theranging functions described below in relation to FIGS. 7-17. Theprocessing circuit 640 may be configured to perform various dataprocessing functions used in wireless communication. The ranging circuit642 may be configured to perform various functions used in rangingoperations in a V2X network. In one example, the ranging circuit 642 maybe configured to transmit and receive ranging signals via thetransceiver 610 and an antenna 616, and determine time-of-arrival (ToA)of received ranging signals based on a local clock 620. In one example,the transceiver 610 may receive, via the antenna 616, a message (e.g.,ranging signal) from another vehicle. The transceiver 610 or thecommunication circuit 644 may convert the message to the baseband thatmay be processed by the processing circuit 640 (e.g., an applicationprocessor and/or a sensor processor) to determine the ToA. Thecommunication circuit 644 may be configured to perform various wirelesscommunication functions using the transceiver 610. The transceiver 610supports wireless communication using unlicensed or licensed UWB and/ornarrowband signals.

Some of the UEs described above in FIGS. 1, 2, and 3 may be vehiclesthat can communicate with each other using V2V or D2D communication.Future generations of vehicles capable of autonomous driving oroperation will demand collision avoidance capability that uses highaccuracy (e.g., centimeter-level accuracy) in vehicle positioning andranging. Aspects of the present disclosure provide a ranging procedurethat enables ranging with high accuracy (e.g., in low-centimeterranges).

FIG. 7 is a schematic diagram illustrating a vehicle 700 capable ofdevice-to-device communications, in accordance with some aspects of thepresent disclosure. In one example, the vehicle 700 can be one of theUEs described in relation to FIGS. 1, 2, and/or 3. The vehicle 700 mayhave a positioning antenna 712, and one or more radio frequency (RF)antennas. For example, the vehicle 700 may have four RF antennas 714,716, 718, and 720, configured to perform vehicle-to-vehicle (V2V)ranging, vehicle-to-everything (V2X) ranging, and/or other wirelesscommunication operations. In other examples, the vehicle 700 may havemore or fewer RF antennas. In one aspect of the disclosure, the RFantennas 714, 716, 718, and 720, may be located at generally theperiphery or edges of the vehicle 700. For example, first and second RFantennas 714 and 716 may be located on the roof of the vehicle 700. Athird RF antenna 720 may be located at the front of the vehicle 700. Afourth RF antenna 718 may be located at the rear of the vehicle 700. Thepositioning antenna 712 may be in operative communication with one ormore navigation satellites (e.g., GNSS satellites). The vehicle 700 mayuse the RF antennas 714, 716, 718, and 720 to communicate with one ormore base stations (for example, one or more eNBs or gNBs as shown inFIGS. 1, 2, and/or 3), or one or more UEs.

FIG. 8 is a schematic diagram illustrating a positioning and rangingsystem 800, in accordance with various aspects of the presentdisclosure. Two exemplary vehicles (e.g., a first vehicle 808 and asecond vehicle 810) are in communication with navigation satellites 802,804 and 806 that can provide the vehicles with satellite positioningsignals. The first vehicle 808 and second vehicle 810 may be any of theUEs illustrated in FIGS. 1, 2, and/or 3. Although only two vehicles areshown in FIG. 8, it should be understood that there may be more or fewervehicles in other examples. The vehicles 808 and 810 are not limited tousing satellite positioning. In some aspects of the disclosure, thevehicles may derive their positions from wireless wide area network(WWAN) signals (e.g., signals from base stations, RSU), visual-basedpositioning, wireless local area network (WLAN) signals (e.g., Wi-Fi,Bluetooth), sensor-based positioning, or any combination thereof.

The first vehicle 808 may be equipped with a positioning antenna, andone or more RF antennas like the vehicle 700 described above in relationto FIG. 7. The vehicle may use the positioning antenna to receivesignals such as satellite signals, WWAN signals, WLAN signals, or acombination thereof. In one example, the RF antennas may be located atthe periphery or edges of the vehicle Similarly, the second vehicle 810may be equipped with a positioning antenna, and one or more RF antennaslike the vehicle 700 shown in FIG. 7.

In one aspect of the disclosure, the first vehicle 808 and the secondvehicle 810 are in operative communication with the navigationsatellites 802, 804, and 806. Although three navigation satellites areshown in FIG. 8, more or fewer navigation satellites may be in operativecommunication with the first vehicle 808 and the second vehicle 810 viatheir respective positioning antennas. Each vehicle can determine itssatellite-based location based on the signals (e.g., time signals)received from the navigation satellites 802, 804, and 806.

In some aspects of the disclosure, the vehicles may improve the accuracyof their determined locations by using a ranging operation in additionto the satellite signals. In one aspect of the disclosure, the firstvehicle 808 may transmit a ranging signal 812 using certain radioparameters (e.g., slot ID) or radio resources Similarly, the secondvehicle 810 may transmit a ranging signal 814 that can be differentiatedfrom the first vehicle's ranging signal 812. In some aspects of thedisclosure, the ranging signal may have a large bandwidth (e.g., 500 MHzto 1 GHz) to enable highly accurate ranging measurements. One exemplarylarge bandwidth signal is an ultra-wideband (UWB) signal. In general, aUWB signal has a low emission level that does not interfere withnarrowband and carrier wave (e.g., cellular carriers) transmissions inthe same or overlapped frequency band. In some examples, a rangingsignal may include a plurality of separate UWB signal pulses sent over alarge bandwidth (e.g., greater than 500 MHz). The radio parameters orradio resources of the ranging signals may be scheduled, allocated, orassigned by a base station (e.g., eNB or gNB) illustrated in FIGS. 1, 2,and/or 3, or any scheduling entity. The first vehicle 808 may use one ormore RF antennas (e.g., antennas 714, 716, 718, and 720 shown in FIG. 7)to receive the ranging signal 814 transmitted by the second vehicle 810.Similarly, the second vehicle 810 may use one or more RF antennas (e.g.,antennas 714, 716, 718, and 720 shown in FIG. 7) to receive the rangingsignal 812 transmitted by the first vehicle 808.

In one aspect of the disclosure, the first vehicle 808 performs aranging operation based on the ranging signal 814 from the secondvehicle 810. Similarly, the second vehicle 810 performs a rangingoperation based on the ranging signal 812 from the first vehicle 808. Inone aspect of the disclosure, the ranging measurements may be obtainedusing the techniques described in connection with FIGS. 9-13 below.Although illustrated as automobiles, the vehicles 808 and 810 may beother types of vehicles, for example, a drone, a manned or an unmannedaerial vehicle, a remote-controlled vehicle, or any other UE or object.

FIG. 9 is a schematic diagram illustrating a communication timeline of aranging protocol 900 in accordance with some aspects of the disclosure.In some examples, this ranging protocol 900 may be used by the vehiclesshown in FIG. 8 to determine a distance between the vehicles. The figurein FIG. 9 illustrates a horizontal axis 902 showing time increasing inthe right direction. The timeline shows a first communication period 906and a second communication period 908. Each communication period 906 or908 may be called a ranging period or measurement period in thisdisclosure. In one aspect of the disclosure, a ranging period may have aduration of about 50 milliseconds. In some examples, the ranging periodmay repeat every 1 or 2 seconds. In other examples, the ranging periodsmay have other durations and/or cycles.

In some aspects of the disclosure, each ranging period includes a firstperiod 910, a second period 912 following the first period, and a thirdperiod 914 following the second period. During the first period 910 (afirst control period), a UE (e.g., vehicle 808) may broadcast its slotID(s) for ranging operations. During the second period 912, the UE maybe in a ranging cycle and transmits one or more ranging signals (e.g.,ranging signals 812 and 814) in a slot(s) associated with the slot ID(s)broadcasted in the first period 910. During the third period 914 (asecond control period), the UE may broadcast ranging information ormeasurements, for example, time-of-arrival (ToA) information, systemdelay information (e.g., transmit (TX) and receive (RX) delay), etc. Inone aspect of the disclosure, the UE may broadcast the slot ID(s) andranging information/measurements using one or more control periods inthe spectrum of a cellular network such as LTE or 5G NR networks.

In some aspects of the disclosure, the UE may transmit ranging signalsusing a large bandwidth (e.g., between 500 MHz and 1 GHz) with a lowpower spectral density. In one example, the ranging signals may be UWBsignals. In a further example, the UE may transmit one or more controlsignals (e.g., slot IDs and ranging information/measurements) in thecontrol periods (i.e., the first control period 910 and second controlperiod 914) using a bandwidth that may be significantly smaller thanthat of the ranging signals. The control signal may be a messagetransmitted using less time and/or frequency resources. For example, theUE may transmit the control signal in the V2X Intelligent TransportSystem (ITS) spectrum, which may have bandwidth of 10 or 20 MHz at 5.9GHz spectrum. Using a large or wider bandwidth such as UWB for theranging signals enables ranging measurements with centimeter orsub-meter accuracy.

FIG. 10 is a schematic diagram illustrating an exemplary ranging cycle1000 in accordance with some aspects of the disclosure. The rangingcycle 1000 may be used in the ranging protocol 900 described andillustrated in relation to FIG. 9. In some examples, the ranging cycle1000 may have a duration that is less than three quarters, one half, orone third of a ranging period. In some examples, the ranging cycle 1000may have a duration that is substantially shorter than a ranging period(e.g., ranging period 906 or 908). In some examples, the ranging cycle1000 may have a duration that is one-tenth or less of the duration ofthe ranging period. In one particular example, the ranging cycle 1000may have a duration of about 5 milliseconds (ms), and a ranging periodmay have a duration of 50 ms or longer.

Each ranging cycle 1000 includes a plurality of time slots eachassociated with a slot ID. Five exemplary time slots (e.g., time slots1002 and 1005) are shown in FIG. 10. In other examples, a ranging cyclemay have more or fewer time slots. In some examples, a time slot mayhave a duration of about 9 microseconds (μs) or any other suitableduration. Each UE (e.g., UEs 808 and 810 of FIG. 8) may transmit one ormore ranging signals 1004 (e.g., UWB pulses) in one or more time slots.In one aspect of the disclosure, the UEs may use different time slots totransmit their respective ranging signals. For example, a first UE maytransmit a ranging signal in a first time slot 1002, and a second UE maytransmit a ranging signal in a different time slot 1005.

In another aspect, a UE may use no more than a predetermined number(e.g., no more than 2) of time slots in a ranging cycle. In some aspectsof the disclosure, a ranging signal 1004 may include UWB pulses thatoccupy a first portion 1006 of the time slot. In FIG. 10, each UWB pulseis represented by an up arrow in the first portion 1006 of a time slot.In one example, the first portion 1006 may have a duration of about 4μs, and the UWB pulses may be distributed in the first portion 1006 witha spacing of about 100 nanoseconds (ns) to 200 ns between pulses. In oneexample, the UWB pulse may have a 500 MHz bandwidth, and each pulse maybe about 2 ns in duration. In this case, a UE may transmit 20 to 40 UWBpulses in a time slot. Using a pulse spacing of about 100 ns to 200 nsallows for multipath propagation of each pulse without significantinterference between different pulses of the same time slot. For a pairof UEs with line-of-sight (LOS), most energy of the multipath is within100 ns to 200 ns.

If the UEs do not have completely or substantially synchronized clocksor time reference, the start time of their ranging signal transmissionsmay not be aligned with the time slot boundary as scheduled by the basestation or scheduling entity. The second portion 1008 of each time slotprovides a guard time to allow for the misalignment without causinginterference among the UEs that use different time slots for theirranging signal transmissions. During the guard time, the UEs do nottransmit ranging signals.

During a ranging cycle 1000, when a UE is not transmitting and not in aTx-to-Rx or Rx-to-Tx transition period, the UE may measure thetime-of-arrival (ToA) of the ranging signals (e.g., UWB pulses)transmitted by other UEs in the same or different time slots. Forexample, after the UE transmitted its ranging signals, the UE canreconfigure its transceiver to receive other UEs ranging signals. TheToAs may be determined with respect to the UE's own clock. In someaspects of the disclosure, the ranging signals (e.g., UWB pulses) fromdifferent UEs have the same waveform or use the same time-frequencyresources. A receiver can distinguish different UEs' ranging signaltransmissions by the time slots used for receiving the ranging signals.In one example, a UE may select (e.g., randomly) the time slot(s) totransmit its ranging signals and signal the time slot assignment toother UEs using the first control period 910 (see FIG. 9) before eachranging cycle. In another example, a scheduling entity may allocate oneor more time slot(s) to the UE. If the UE cannot successively receive aranging signal, the UE may receive the ranging signal in the nextranging cycle.

FIG. 11 is a schematic diagram illustrating exemplary ranging signaltransmissions during a ranging cycle in accordance with some aspects ofthe disclosure. Three exemplary time slots of the ranging cycle 1000 areillustrated in FIG. 11. In other examples, the ranging cycle 1000 mayhave more or fewer time slots. During a first time slot, a first UE 1102(UE1) transmits its ranging signals, and a second UE 1104 (UE2) and athird UE 1106 (UE3) each determine the TOA of UE1's ranging signals.During a second time slot, UE2 transmits its ranging signals, and UE1and UE3 each determine the TOA of UE2's ranging signals. During a thirdtime slot, UE3 transmits its ranging signals, and UE1 and UE2 eachdetermine the TOA of UE3's ranging signals.

FIG. 12 is a diagram illustrating a resource allocation example for aranging period 1200 in accordance with some aspects of the disclosure.The ranging period 1200 may be the same as the communication period 906or 908 of FIG. 9. In one example, the resource allocated to the rangingperiod 1200 may include network resources (e.g., time-frequencyresources) that can be used for direct vehicle-to-vehicle (V2V) and/orvehicle-to-everything (V2X) communication. In some examples, theseresources may be sidelink resources of the RAN 200. A UE (e.g., vehicle)can communicate directly with another vehicle or device via a sidelinkIn FIG. 12, the horizontal axis shows a time domain, and the verticalaxis shows a frequency domain. A scheduling entity (e.g., eNB, gNB, basestation, a vehicle, a server, a traffic light, and/or an RSU) mayallocate resources for the ranging period 1200, including sidelinkresources.

In some aspects of the disclosure, the ranging period 1200 has a firstperiod 1202, a second period 1204, and a third period 1206 that aresimilar to the periods 910, 912 and 914 shown in FIG. 9. In the firstperiod 1202 (a first control period), a UE may transmit and/or receivecontrol information using a physical sidelink control channel (PSCCH)1208 and payload data using a physical sidelink shared channel (PSSCH)1210. The PSCCH 1208 may contain information about the resource and MCS(modulation and coding scheme) used by the corresponding PSSCH 1210. Thescheduling entity may allocate the PSCCH/PSSCH of different UEs todifferent resources. In some examples, a UE may broadcast its rangingsignal slot ID(s) in the PSSCH 1210. The slot ID indicates the slot inthe ranging cycle 1204 that is used for transmitting the UE's rangingsignal. A base station (e.g., eNB or gNB) may schedule different UEs touse different time and/or frequency resources for their respective PSCCH1208 and the PSSCH 1210 to transmit their respective information. When aUE is not transmitting in the first period 1202, the UE can receive theslot IDs broadcasted by other UEs.

In the third period 1206 (a second control period), a UE may transmitcontrol information in a PSCCH 1212, during which the UE may broadcastresource information, MCS information, etc. The UE may also transmitdata in a corresponding PSSCH 1214. The scheduling entity may allocatethe PSCCH/PSSCH of different UEs to different resources. For example,the UE may broadcast its ranging information such as ToA information,transmit (TX) and receive (RX) delay, etc. The ToA information, the TXand RX delay, and other information may be determined by the UE duringtimes when the UE is not transmitting a ranging signal and not in aTX-to-RX or RX-to-TX transition period. A base station may scheduledifferent UEs to use different time and/or frequency resources for thePSCCH 1212 and the PSSCH 1214 to transmit their respective informationin the third period 1206. When a UE is not transmitting in the thirdperiod 1206, the UE can receive the ToA information and TX/RX delayinformation broadcasted by other UEs.

In the second period 1204, a UE may transmit a ranging signal (e.g., UWBpulses), for example, in a physical sidelink ranging channel (PSRCH)1216 in one or more time slot(s) 1218 associated with its time slotID(s) broadcasted in the first period 1202. That is, different UEstransmit their ranging signals in different and distinct time slots inthe PSRCH 1216 during a ranging cycle. A receiver can distinguish theranging signals from different UEs by the slots in which they arereceived. In a sense, the ranging signals are time-multiplexed. In someexamples, the UEs can send the same UWB pulses (e.g., same frequency,bandwidth, and power) as the ranging signals in different time slots. Insome examples, the scheduling entity or base station may allocate thePSRCH 1216 to different frequency resources (e.g., subcarriers) indifferent time slots.

Although the PSCCH, PSSCH, and PSRCH communications are illustrated asfilling specific radio resources in FIG. 12, it is understood that thePSCCH, PSSCH, and PSRCH communications can utilize other radio resourceallocation schemes. In some aspects of the disclosure, a UE can use acellular or licensed spectrum (e.g., LTE and 5G NR spectrum) for thePSCCH and PSSCH in the first period 1202 and third period 1206, and aUWB spectrum or unlicensed spectrum for the PSRCH 1216.

During the ranging cycle 1206, when a UE is not transmitting and not ina TX-to-RX or RX-to-TX transition period, the UE may attempt todetermine the ToA of the ranging signals from other UEs. The UE maymeasure the ToAs with respect to the UE's own local clock or timereference.

In some aspects of the disclosure, a first UE (e.g., UE 808 of FIG. 8)may transmit (e.g., broadcast) ToA information and TX/RX delayinformation in the third period 1206 to allow at least one second UE(e.g., UE 810 of FIG. 8), to cancel the clock or time offset between theUEs and allow the second UE to determine the distance between the UEs.However, in some scenarios, the second UE may not be interested in thedistance between the UEs. Therefore, in such a scenario, the first UEmay not need to transmit ToA information in the third period 1206. Anexample is V2I (Vehicle-to-Infrastructure) ranging, where a UE (e.g., avehicle) attempts to estimate the distances from a number of RSUs(roadside units) with known positions (e.g., GNSS positions), andsubsequently estimates its own position. In this example, only the RSUstransmit information (e.g., ToA and/or TX/RX delays) in the third period1206. A vehicle can estimate its distance from an RSU after receivingthe ToA and optionally TX/RX delay information from the RSU.

In one example, the UE can receive ranging information from at leastthree RSUs with known positions to determine the position of the UE. Inanother example, the UE may receive ranging information and precisepositions (e.g., sub-meter accuracy) of three or more other vehicles todetermine a position of the UE. In this example, the other vehicles maydetermine their precise positions using a combination of visualpositioning, carrier phase GNSS positioning, etc. In some examples, evenif a precise position is not known for nearby vehicles, the UE candifferentiate where another vehicle is relative (e.g., the vehicle is infront or behind the UE, etc.) to the UE using other techniques such asdoppler effects.

FIG. 13 is a timing diagram 1300 illustrating ToA determination ofranging signals in accordance with some aspects of the disclosure. Thetiming diagram 1300 shows a first UE (UE 1) and a second UE (UE 2) eachtransmitting a ranging signal. In one example, the first UE may be thevehicle 808 of FIG. 8, and the second UE may be the vehicle 810 of FIG.8. Due to clock or time offsets between the first and second UEs, theToAs measured by each UE may not reflect the actual ranging signalpropagation time 1302. To compensate for or cancel the clock/timeoffset, after the ranging cycle, each UE can broadcast to other UEs itsmeasured ToAs and optionally its own TX/RX chain delays on each of itsRF antennas, during the third time period 1206 (see FIG. 12). The TX/RXchain delays of a UE may be constant parameters specific to the UE andmay be measured and stored on the UE beforehand. This information can beused to compensate for or cancel clock offsets when calculating theranges or distances between UEs. Alternatively, the UE may firstinternally adjust the ToA measurements using its TX/RX chain delays andbroadcast its adjusted ToAs to other UEs.

In one example, each of UE 1 and UE 2 broadcasts a ranging signal 1304as shown FIG. 13. The nominal transmission time for UE 1′s rangingsignal is shown as T1, and the nominal transmission time for UE 2'sranging signal is shown as T2. The measured ToA of the ranging signalsent by UE 1 as received at UE 2 is referred to as time t1, and themeasured ToA of the ranging signal sent by UE 2 as received by UE 1 isreferred to as time t2. The clock offset of UE 1 is referred to as pl,and the clock offset of UE 2 is referred to as p2. The TX/RX chain delay(if used) of UE 1 is referred to respectively as q_tx1 and q_rx1, andthe TX/RX chain delay (if used) of UE 2 is referred to respectively asq_tx2 and q_rx2. The distance between UE 1 and UE 2 is referred to asdl2, and the speed of light is referred to as c.

Accordingly, t1 and t2 can be determined as follows:

t1=T1+p1+q_tx1+dl2/c+q_rx2−p2   Equation 1

t2=T2+p2+q_tx2+dl2/c+q_rx1−p1   Equation 2

Equation 1 shows that UE 1 transmits its ranging signal at nominal timeT1 (i.e., time T1 according to its local clock). If its clock has anoffset of p1 compared to the true time, UE 1 actually transmits at timeT1+p1. After the delay (q_tx1) of UE 1's TX chain, the propagation timedl2/c, and the delay (q_rx2) at UE 2's Rx chain, the ranging signal isreceived by UE 2 at time T1+p1+q_tx1+dl2/c+q_rx2. However, due to UE 2'sclock offset (p2), the ToA measured by UE 2 is further adjusted by p2.

Equation 2 shows that UE 2 transmits its ranging signal at nominal timeT2 (i.e., time T2 according to its local clock). If its clock has anoffset of p2 compared to the true time, UE 2 actually transmits at timeT2+p2. After the delay (q_tx2) at UE 2's TX chain, the propagation timedl2/c, and the delay (q_rx1) at UE 1's Rx chain, the ranging signal isreceived by UE 1 at time T2+p2+q_tx2+dl2/c+q_rx1. However, due to UE 1'sclock offset (p1), the ToA measured by UE 1 is further adjusted by p1.

Adding the two equations together, the clock offsets p1 and p2 arecanceled out. Rearranging the terms results in:

dl2=c((t1−T1)+(t2−T2)−(q_tx1+q_rx1)−(q_tx2+q_rx2))/2.   Equation 3

Therefore, if UE 1 broadcasts the ToA (t2) and the sum of its TX/RXchain delay q_tx1+q_rx1, and UE 2 broadcasts its ToA (t1) and the sum ofits TX/RX chain delay q_tx2+q_rx2, both UEs can compute dl2 (range)according to the above equation. Note that T1 and T2 are known to bothUEs because the associated time slot IDs are broadcast before theranging cycle.

Alternatively, UE 1 can broadcast an adjusted ToA t2′=t2−(q_tx1+q_rx1),and UE 2 can broadcast an adjusted ToA t1′=t1−(q_tx2+q_rx2). In thisexample, the distance dl2 can be computed as:

dl2=c((t1′−T1)+(t2′−T2))/2.   Equation 4

FIG. 14 is a flow chart illustrating an exemplary process 1400 forperforming a ranging operation between UEs in accordance with someaspects of the present disclosure. As described below, some or allillustrated features may be omitted in a particular implementationwithin the scope of the present disclosure, and some illustratedfeatures may not be required for implementation of all embodiments. Insome examples, the process 1400 may be carried out by a UE or vehicleillustrated in any of FIGS. 1, 2, 3, 7, 8, and/or 11. In some examples,the UE or vehicle may be the scheduling entity 500 illustrated in FIG.5. In some examples, the UE or vehicle may be the scheduled entity 600illustrated in FIG. 6. In some examples, the process 1400 may be carriedout by any suitable apparatus or means for carrying out the functions,procedures, or algorithm described below.

At block 1402, a first UE may transmit a first slot ID in a firstcontrol period, to indicate a first time slot for transmitting a firstranging signal in a ranging cycle after the first control period. Theranging cycle includes a plurality of time slots including the firsttime slot and a second time slot. In one example, the first UE may bethe vehicle 808 that uses a ranging circuit 642 and/or the transceiver610 (see FIG. 6) to broadcast a slot ID in a PSSCH 1210 in a firstcontrol period 1202 as shown in FIG. 12. The slot ID indicates the timeslot in which the UE transmits a ranging signal in an upcoming rangingcycle 1204 (See FIG. 12).

At block 1404, the first UE may use the transceiver 610 to transmit thefirst ranging signal in the first time slot in the ranging cycle. Forexample, the first time slot may be a time slot 1218 in a PSRCH 1216(see FIG. 12) allocated to the first UE for transmitting the rangingsignal. The time slot may be one of a plurality of time slots in aranging cycle, for example, illustrated in FIG. 10. In some examples,the ranging signal may include a number of UWB pulses with a bandwidthgreater than narrowband carrier signals (e.g., 500 MHz).

At block 1406, the first UE may use the transceiver 610 to receive, froma second UE, a second ranging signal in the second time slot that isdifferent from the first time slot in the ranging cycle. For example,the second UE may be the vehicle 810 (see FIG. 8) that transmits aranging signal 814 (see FIG. 8) in an allocated time slot in the PSRCH1216. The ranging signals of the first UE and second UE are transmittedin different time slots of the ranging cycle (e.g., ranging cycle 1000of FIG. 10).

At block 1408, the first UE may use the ranging circuit 642 to determinea first ToA of the second ranging signal when received by the first UE.The first ToA may be the time when the first UE receives the secondranging signal. The first UE may determine the first ToA (e.g., t2 ofFIG. 13) based on its local clock or time reference as described abovein relation to FIG. 13. Similarly, the second UE determines a second ToAof the first ranging signal when received by the second UE. The secondToA may be the time when the second UE receives the first ranging signalfrom the first UE. The second UE may determine the second ToA (e.g., t1of FIG. 13) based on its local clock or time reference as describedabove in relation to FIG. 13.

At block 1410, the first UE may use the transceiver 610 to transmit thefirst ToA in a second control period after the ranging cycle. Forexample, the first UE may transmit the first ToA in a PSSCH 1214 in asecond control period 1206 as shown in FIG. 12. In the second controlperiod, the first UE may receive the second ToA broadcast from thesecond UE for the first UE's ranging signal.

FIG. 15 is a flow chart illustrating another exemplary process 1500 forperforming a ranging operation among a plurality of UEs in accordancewith some aspects of the present disclosure. As described below, some orall illustrated features may be omitted in a particular implementationwithin the scope of the present disclosure, and some illustratedfeatures may not be required for implementation of all embodiments. Insome examples, the process 1500 may be carried out by a UE or vehicleillustrated in any of FIGS. 1, 2, 3, 7, 8, and/or 11. In some examples,the UE or vehicle may be the scheduling entity 500 illustrated in FIG.5. In some examples, the UE or vehicle may be the scheduled entity 600illustrated in FIG. 6. In some examples, the process 1500 may be carriedout by any suitable apparatus or means for carrying out the functions,procedures, or algorithm described below.

At block 1502, a UE determines an allocation of a plurality of timeslots of a ranging cycle. For example, the UE may be one of a pluralityof UEs capable of performing V2X ranging operation in a ranging cycle1000. In the time slot allocation, each of the UEs is allocated to oneor more of the plurality of time slots for transmitting a rangingsignal. The UE may use a ranging circuit 642 to determine theallocation.

At block 1504, the UE transmits the ranging signal in each allocatedtime slot. In one example, each UE transmits a ranging signal in thecorresponding time slot(s). The ranging signal may be a plurality of UWBpulses 1004 (see FIG. 10) distributed in time the slot. The UE may usethe transceiver 610 to transmit the ranging signal.

At block 1506, the UE receives, from each other UE, the ranging signalin the corresponding time slots allocated to the other UEs. The UE mayuse the transceiver 610 to receive the ranging signals. At block 1508,the UE receives, from the other UE using the transceiver 610, a firstToA of the ranging signal when received by the other UE. The UE mayreceive a ToA from each other UE. At block 1510, the UE determines asecond ToA of the ranging signal when received from the other UE. The UEmay use the ranging circuit 642 to determine a ToA for each receivedranging signal. At block 1512, the UE may use the ranging circuit 642 todetermine a distance between the UEs based on the first ToA and thesecond ToA. That is, the UE can determine a distance (range) betweenitself and each other UE.

FIG. 16 is a diagram illustrating a positioning process based on rangingin accordance with some aspects of the present disclosure. As describedbelow, some or all illustrated features may be omitted in a particularimplementation within the scope of the present disclosure, and someillustrated features may not be required for implementation of allembodiments. In some examples, the positioning process may be performedby any of the UEs, devices, or vehicles illustrated in any of FIGS. 1,2, 3, 5-8, and/or 11 to determine a position using multilateration.

Referring to FIG. 16, a first UE 1602 may transmit a ranging signal R1for ranging operations. The first UE 1602 may receive ranging signalsfrom three or more UEs or devices, for example, a ranging signal R2 froma second UE 1604, a ranging signal R3 from a third UE 1606, and aranging signal R4 from a fourth UE 1608. These ranging signals (R1, R2,R3, R4) may be UWB ranging signals similar to those described above inrelation to FIG. 10. The first UE can determine the distances (e.g., D1,D2, and D3) from the second, third, and fourth UEs using the rangingmethods described above in relation to FIGS. 12-15. If the first UEknows the accurate positions (e.g., geographic coordinates) of thesecond, third, and fourth UEs, the first UE can determine its ownaccurate position, for example, using multilateration techniques basedon the known positions and distances of the other UEs. In one example,the second, third, and fourth UEs may be RSUs or other fixed deviceswith their accurate positions known by the first UE. In another example,the second, third, and fourth UEs may have the capability to determineand report their respective accurate positions, for example, using GNSSbased methods, visual, and/or other suitable methods. The first UE mayreceive the other UEs' positions via V2V communication.

FIG. 17 is a flow chart illustrating an exemplary process 1700 fordetermining a position of a device using a ranging based method inaccordance with some aspects of the present disclosure. As describedbelow, some or all illustrated features may be omitted in a particularimplementation within the scope of the present disclosure, and someillustrated features may not be required for implementation of allembodiments. In some examples, the process 1700 may be carried out by anapparatus (e.g., UE or vehicle) illustrated in any of FIGS. 1, 2, 3,5-8, 11, and/or 16. In some examples, the apparatus may be thescheduling entity 500 illustrated in FIG. 5. In some examples, theapparatus may be the scheduled entity 600 illustrated in FIG. 6. In someexamples, the process 1700 may be carried out by any suitable apparatusor means for carrying out the functions, procedures, or algorithmdescribed below.

At block 1702, a first UE (e.g., UE 1602 of FIG. 16) determines anallocation of a plurality of time slots of a ranging cycle for aplurality of UEs. Each UE is allocated to one or more of the pluralityof time slots for transmitting a ranging signal. For example, theranging cycle may be the ranging cycle described above in relation toFIGS. 9-10. The first UE may use the ranging circuit 642 to determinethe allocation of the time slots and the corresponding UEs.

At block 1704, the first UE transmits a first ranging signal in a timeslot allocated to the first UE. The first UE may use the transceiver 610to transmit the first ranging signal to other UEs (e.g., UE 1604, UE1606, and UE 1608 of FIG. 16). In some examples, the first rangingsignal may be a UWB signal including a number of UWB signal pulses. Atblock 1706, the first UE receives a second ranging signal, associatedwith each of the other UEs, in each time slot allocated to the otherUEs. The first UE may use the transceiver 610 to receive the secondranging signal. In some examples, the second ranging signal may be a UWBsignal including a number of UWB signal pulses.

At block 1708, the first UE determines a plurality of first ToAs for theother UEs. Each of the first ToAs is based on a time the second rangingsignal associated with each of the other UEs is received. The first UEmay use the ranging circuit 642 and/or processing circuit 640 todetermine the first ToAs. At block 1710, the first UE receives aplurality of second ToAs of the first ranging signal. Each of the secondToAs corresponds to a time when the other UE received the first rangingsignal. The first UE may use the transceiver 610 to receive theplurality of second ToAs, for example, in a control period after theranging cycle.

At block 1712, the first UE determines a position of the first UE basedon the plurality of first ToAs and the plurality of second ToAs. Forexample, the first UE may use the ranging circuit 642 and/or processingcircuit 640 to determine the position of the first UE using amultilateration algorithm based on the first ToAs and second ToAs.

In one configuration, the apparatus 500 and/or 600 for wirelesscommunication includes various means for performing the rangingfunctions and various procedures described in relation to FIGS. 7-17. Inone aspect, the aforementioned means may be the processor(s) 504 or 604in FIG. 5 or 6 configured to perform the functions recited by theaforementioned means. In another aspect, the aforementioned means may bea circuit or any apparatus configured to perform the functions recitedby the aforementioned means.

Of course, in the above examples, the circuitry included in theprocessor 504 or 604 is merely provided as an example, and other meansfor carrying out the described functions may be included within variousaspects of the present disclosure, including but not limited to theinstructions stored in the computer-readable storage medium 506/606, orany other suitable apparatus or means described in any one of the FIGS.1, 2, 3-8, 11, and/or 16, and utilizing, for example, the processesand/or algorithms described herein in relation to FIGS. 7-17.

Several aspects of a wireless communication network have been presentedwith reference to an exemplary implementation. As those skilled in theart will readily appreciate, various aspects described throughout thisdisclosure may be extended to other telecommunication systems, networkarchitectures and communication standards.

By way of example, various aspects may be implemented within othersystems defined by 3GPP, such as Long-Term Evolution (LTE), the EvolvedPacket System (EPS), the Universal Mobile Telecommunication System(UMTS), and/or the Global System for Mobile (GSM). Various aspects mayalso be extended to systems defined by the 3rd Generation PartnershipProject 2 (3GPP2), such as CDMA2000 and/or Evolution-Data Optimized(EV-DO). Other examples may be implemented within systems employing IEEE802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Ultra-Wideband (UWB),Bluetooth, and/or other suitable systems. The actual telecommunicationstandard, network architecture, and/or communication standard employedwill depend on the specific application and the overall designconstraints imposed on the system.

Within the present disclosure, the word “exemplary” is used to mean“serving as an example, instance, or illustration.” Any implementationor aspect described herein as “exemplary” is not necessarily to beconstrued as preferred or advantageous over other aspects of thedisclosure. Likewise, the term “aspects” does not require that allaspects of the disclosure include the discussed feature, advantage ormode of operation. The term “coupled” is used herein to refer to thedirect or indirect coupling between two objects. For example, if objectA physically touches object B, and object B touches object C, thenobjects A and C may still be considered coupled to one another—even ifthey do not directly physically touch each other. For instance, a firstobject may be coupled to a second object even though the first object isnever directly physically in contact with the second object. The terms“circuit” and “circuitry” are used broadly, and intended to include bothhardware implementations of electrical devices and conductors that, whenconnected and configured, enable the performance of the functionsdescribed in the present disclosure, without limitation as to the typeof electronic circuits, as well as software implementations ofinformation and instructions that, when executed by a processor, enablethe performance of the functions described in the present disclosure.

One or more of the components, steps, features and/or functionsillustrated in FIGS. 1-17 may be rearranged and/or combined into asingle component, step, feature or function or embodied in severalcomponents, steps, or functions. Additional elements, components, steps,and/or functions may also be added without departing from novel featuresdisclosed herein. The apparatus, devices, and/or components illustratedin FIGS. 1-17 may be configured to perform one or more of the methods,features, or steps described herein. The novel algorithms describedherein may also be efficiently implemented in software and/or embeddedin hardware.

It is to be understood that the specific order or hierarchy of steps inthe methods disclosed is an illustration of exemplary processes. Basedupon design preferences, it is understood that the specific order orhierarchy of steps in the methods may be rearranged. The accompanyingmethod claims present elements of the various steps in a sample order,and are not meant to be limited to the specific order or hierarchypresented unless specifically recited therein.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but are to be accorded the full scope consistentwith the language of the claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” Unless specifically statedotherwise, the term “some” refers to one or more. A phrase referring to“at least one of” a list of items refers to any combination of thoseitems, including single members. As an example, “at least one of: a, b,or c” is intended to cover: a; b; c; a and b; a and c; b and c; and a, band c. All structural and functional equivalents to the elements of thevarious aspects described throughout this disclosure that are known orlater come to be known to those of ordinary skill in the art areexpressly incorporated herein by reference and are intended to beencompassed by the claims. Moreover, nothing disclosed herein isintended to be dedicated to the public regardless of whether suchdisclosure is explicitly recited in the claims. No claim element is tobe construed under the provisions of 35 U.S.C. § 112(f) unless theelement is expressly recited using the phrase “means for” or, in thecase of a method claim, the element is recited using the phrase “stepfor.”

What is claimed is:
 1. A first user equipment (UE), comprising: atransceiver configured for performing ranging using a ranging periodcomprising a first control period, a ranging cycle, and a second controlperiod; a memory; and a processor operatively coupled with thetransceiver and the memory, wherein the processor and the memory areconfigured to: transmit, via the transceiver, a first slot ID in thefirst control period, to indicate a first time slot for transmitting afirst ranging signal in the ranging cycle after the first controlperiod, the ranging cycle comprising a plurality of time slots includingthe first time slot and a second time slot; transmit, via thetransceiver, the first ranging signal in the first time slot in theranging cycle; receive, from a second user equipment (UE) via thetransceiver, a second ranging signal in the second time slot that isdifferent from the first time slot; determine a first time-of-arrival(ToA) of the second ranging signal when received by the first UE; andtransmit, via the transceiver, the first ToA in the second controlperiod after the ranging cycle.
 2. The first UE of claim 1, wherein theprocessor and the memory are further configured to transmit, via thetransceiver, the first slot ID in a first spectrum, transmit, via thetransceiver, the first ToA in the first spectrum, and transmit, via thetransceiver, the first ranging signal in a second spectrum that is widerthan the first spectrum.
 3. The first UE of claim 2, wherein the firstspectrum comprises a licensed spectrum, and the second spectrumcomprises an unlicensed spectrum.
 4. The first UE of claim 1, whereinthe first ranging signal comprises one or more ultra-wideband (UWB)pulses distributed in the first time slot.
 5. The first UE of claim 4,wherein each of the plurality of time slots comprises a guard time. 6.The first UE of claim 1, wherein the first ranging signal comprises afirst ultra-wideband (UWB) signal, and wherein the second ranging signalcomprises a second UWB signal that uses same network resources as thefirst UWB signal.
 7. The first UE of claim 1, wherein the processor andthe memory are further configured to: receive, from the second UE viathe transceiver, a second slot ID in the first control period; identifythe second time slot for receiving the second ranging signal in theranging cycle based on the second slot ID; and receive, from the secondUE via the transceiver, a second ToA of the first ranging signal whenreceived by the second UE.
 8. The first UE of claim 7, wherein theprocessor and the memory are further configured to: determine a distancebetween the first UE and the second UE based on the first ToA and thesecond ToA.
 9. The first UE of claim 8, wherein the processor and thememory are further configured to: compensate for a clock offset betweenthe first UE and the second UE.
 10. The first UE of claim 1, wherein theprocessor and the memory are further configured to: receive, via thetransceiver, a plurality of ranging signals from a plurality of userequipments (UEs) including the second UE, the ranging signalsrespectively received in distinct time slots of the plurality of timeslots in the ranging cycle.
 11. A first user equipment (UE) for wirelesscommunication, comprising: a transceiver configured for performingranging with a plurality of user equipments (UEs) including a second UE;a memory; and a processor operatively coupled with the transceiver andthe memory, wherein the processor and the memory are configured to:determine an allocation of a plurality of time slots of a ranging cycle,each of the plurality of UEs allocated to one or more of the pluralityof time slots for transmitting a ranging signal; transmit, via thetransceiver, a first ranging signal in a time slot allocated to thefirst UE; receive, from the second UE via the transceiver, a secondranging signal in a time slot allocated to the second UE; receive, fromthe second UE via the transceiver, a first time-of-arrival (ToA) of thefirst ranging signal when received by the second UE; determine a secondToA of the second ranging signal when received by the first UE; anddetermine a distance between the first UE and the second UE based on thefirst ToA and the second ToA.
 12. The UE of claim 11, wherein theprocessor and the memory are further configured to: adjust the first ToAand the second ToA to compensate for a time offset between the first UEand the second UE.
 13. A method of performing ranging at a first userequipment (UE) during a ranging period comprising a first controlperiod, a ranging cycle, and a second control period, the methodcomprising: transmitting a first slot ID in the first control period, toindicate a first time slot for transmitting a first ranging signal inthe ranging cycle after the first control period, the ranging cyclecomprising a plurality of time slots including the first time slot and asecond time slot; transmitting the first ranging signal in the firsttime slot in the ranging cycle; receiving, from a second user equipment(UE), a second ranging signal in the second time slot that is differentfrom the first time slot; determining a first time-of-arrival (ToA) ofthe second ranging signal when received by the first UE; andtransmitting the first ToA in the second control period after theranging cycle.
 14. The method of claim 13, wherein the transmitting thefirst slot ID comprises transmitting the first slot ID in a firstspectrum, wherein the transmitting the first ToA comprises transmittingthe first ToA in the first spectrum, and wherein the transmitting thefirst ranging signal comprises transmitting the first ranging signal ina second spectrum that is wider than the first spectrum.
 15. The methodof claim 14, wherein the first spectrum comprises a licensed spectrum,and the second spectrum comprises an unlicensed spectrum.
 16. The methodof claim 13, wherein the first ranging signal comprises one or moreultra-wideband (UWB) pulses distributed in the first time slot.
 17. Themethod of claim 16, wherein each of the plurality of time slotscomprises a guard time.
 18. The method of claim 13, wherein the firstranging signal comprises a first ultra-wideband (UWB) signal, andwherein the second ranging signal comprises a second UWB signal thatuses same network resources as the first UWB signal.
 19. The method ofclaim 13, further comprising: receiving, from the second UE, a secondslot ID in the first control period; identifying the second time slotfor receiving the second ranging signal in the ranging cycle based onthe second slot ID; and receiving, from the second UE, a second ToA ofthe first ranging signal when received by the second UE.
 20. The methodof claim 19, further comprising: determining a distance between thefirst UE and the second UE based on the first ToA and the second ToA.21. The method of claim 20, wherein the determining the distancecomprises: compensating for a clock offset between the first UE and thesecond UE.
 22. The method of claim 13, further comprising: receiving aplurality of ranging signals from a plurality of user equipments (UEs)including the second UE, the ranging signals respectively received indistinct time slots of the plurality of time slots in the ranging cycle.23. A method of performing ranging among a plurality of user equipments(UEs) including a first UE and a second UE, the method comprising:determining an allocation of a plurality of time slots of a rangingcycle, each of the plurality of UEs allocated to one or more of theplurality of time slots for transmitting a ranging signal; transmittinga first ranging signal in a time slot allocated to the first UE;receiving, from the second UE, a second ranging signal in a time slotallocated to the second UE; receiving, from the second UE, a firsttime-of-arrival (ToA) of the first ranging signal when received by thesecond UE; determining a second ToA of the second ranging signal whenreceived by the first UE; and determining a distance between the firstUE and the second UE based on the first ToA and the second ToA.
 24. Themethod of claim 23, further comprising: adjusting the first ToA and thesecond ToA to compensate for a time offset between the first UE and thesecond UE.